import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';
// 函数组件不需要存值就能这么写，不需要state，只起到接受父类的值和执行父类的方法
function Square(props){
  /**
   * 在 JavaScript class 中，每次你定义其子类的构造函数时，都需要调用 super 方法。
   * 因此，在所有含有构造函数的的 React 组件中，构造函数必须以 super(props) 开头。
   *  */ 
  // constructor(props) {
  //   super(props);
  //   this.state = {
  //     value : null
  //   };
  // }
    return (
      <button
        className="square"
        onClick={ props.onClick }
      >
        { props.value }
      </button>
    )
}

class Board extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      squares: Array(9).fill(null),
      xIsNext:true
    }
  }
  handleClick(i) {
    console.log('i',i);
    const squares = this.state.squares.slice()
    // 当有玩家胜出时，或者某个 Square 已经被填充时，该函数不做任何处理直接返回
    if (calculateWinner(squares) || squares[i]) {
      return;
    }
    console.log('',squares,this.state);
    squares[i] =this.state.xIsNext?'X':'O'
    this.setState({squares,xIsNext:!this.state.xIsNext})
  }
  renderSquare(i) {
    return <Square
      value={this.state.squares[i]} 
      onClick = {()=>this.handleClick(i)}
      />;
  }

  render() {
    const winner = calculateWinner(this.state.squares);
    let status;    
    if (winner) {
      status = 'Winner: ' + winner;
    } else {
      status = 'Next player: ' + (this.state.xIsNext ? 'X' : 'O');
    }
    return (
      <div>
        <div className="status">{status}</div>
        <div className="board-row">
          {this.renderSquare(0)}
          {this.renderSquare(1)}
          {this.renderSquare(2)}
        </div>
        <div className="board-row">
          {this.renderSquare(3)}
          {this.renderSquare(4)}
          {this.renderSquare(5)}
        </div>
        <div className="board-row">
          {this.renderSquare(6)}
          {this.renderSquare(7)}
          {this.renderSquare(8)}
        </div>
      </div>
    );
  }
}

class Game extends React.Component {
  render() {
    return (
      <div className="game">
        <div className="game-board">
          <Board />
        </div>
        <div className="game-info">
          <div>{/* status */}</div>
          <ol>{/* TODO */}</ol>
        </div>
      </div>
    );
  }
}

function calculateWinner(squares) {
  const lines = [
    [0, 1, 2],
    [3, 4, 5],
    [6, 7, 8],
    [0, 3, 6],
    [1, 4, 7],
    [2, 5, 8],
    [0, 4, 8],
    [2, 4, 6],
  ]
  for (let i = 0; i < lines.length; i++) {
    const [a, b, c] = lines[i];
    if (squares[a] && squares[a] === squares[b] && squares[a] === squares[c]) {
      return squares[a];
    }
  }
  return null;
}
// ========================================

ReactDOM.render(
  <Game />,
  document.getElementById('root')
);


// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitals
reportWebVitals();
